Photographic cameras are known which can expose intermixed image frames of different aspect ratios on the same film strip. As shown in FIG. 2, for 35 mm film these are typically full size size image frames 60, 66 with an aspect ratio of 24.times.36 mm and panoramic size image frames 62, 64 with an aspect ratio of approximately 13.times.36 mm. The reduced vertical dimension of the panoramic image frame is achieved in the camera by masking off the upper and lower portions of the exposure frame leaving unexposed spaces 70 above and below the panoramic image area on the film of a minimum film density value Dmin. When applied to a photographic printer, the panoramic image frame is magnified to be printed typically to a 3.5.times.10 inch (8.9.times.25.4 cm) or 4.times.12 inch (10.2.times.30.5 cm) positive print.
Currently on automatic photographic printers, however, the interspersed panoramic image frame are printed incorrectly. Since, the panoramic frames are intermixed with the standard full size image frames, the panoramic frames are printed to the full frame aspect ratio, typically 3.5.times.5 inches (8.9.times.12.2 cm). The resultant print is not only the incorrect size but also has large black strips on the top and bottom of the print. Thus there is a need for automatic printers, especially those that run at high speeds, to provide an automatic technique for recognizing the existence of a panoramic image frame so that the printer may print the image frame with the correct magnification and aspect ratio, or likely flag the frame to be skipped and printed later on another printer having suitable provision for printing panoramic image frames correctly.
High speed photographic printers operate at extremely high print rates. For example, the CLAS35 High Speed Printer produced by Eastman Kodak Company has a burst rate of 27,000 prints per hour. This corresponds to only 133 milliseconds per frame. Because of this any technique for automatically recognizing panoramic image frames must be very time efficient so that the printer's productivity is not adversely effected.
Commonly assigned U.S. Pat. No. 5,289,229, describes a technique for recognizing panoramic image frames interspersed on a film strip among full size image frames. In this disclosure, the film strip is scanned at a scan station in conventional manner to produce image pixel scan data used to derive exposure determination information for control of the exposure of the image frame to the print paper. Additionally, for image discrimination purposes, the scan data from a central region of the image frame are used to determine if an image exists in the image frame area. If so, then discrimination of the image between full size and panoramic format is performed. For this purpose, the scan data from upper and lower areas corresponding to areas 70 in FIG. 2 are tested to determine if image information exists in these outer areas and, if not, then a determination is made that a panoramic image frame exists. While this latter technique is theoretically capable of discriminating between panoramic and full size image frames for some scene images, it has been found that the reliability with which such discrimination can be made for the wide variety of scene images encountered in actual practice is somewhat limited and is therefore unsatisfactory for actual commercial application.
There is therefore a need for a reliable technique for use in automatic photographic printers for automatically discriminating between panoramic and full size image frames interspersed on the same film strip. There is a further need for such a technique that can be used in high speed printers without adversely affecting productivity of such printers. The present invention satisfies these needs.